Functional Safety Description - Rockwell Automation Allen-Bradley Compact GuardLogix 5370 Controller Application Technique

Door Locking and Monitoring with a 442G Access Box and an Integrated Safety Controller Safety Function
Considerations for Safety Distance and Stopping Performance
Safety distance calculations are typically not required for safety functions that use a Power-to-release locking-gate switch.
The risk assessment determines if a safety distance calculation is required for your safety function that uses the
Multifunctional Access Box.
Based on the selection of a sensor subsystem, the risk assessment determines if a safety distance calculation is required.
Typically, a safety distance calculation is required if a non-separating sensor subsystem (such as a light curtain) is selected
for the safety function. If a safety distance calculation is required for this safety function, the following documents can be
referenced:
• GuardLogix 5570 and Compact GuardLogix 5370 Controller Systems Safety Reference Manual,
publication1756-RM099
• SafeBook 5– Safety related control systems for machinery, publication
• Safety Function: Light Curtain Products: Light Curtain GuardLogix Controller, publication

Functional Safety Description

In this example, an unlock is requested by pressing an Unlock Request button on the MAB. The unlock request is sent
over a CIP Safety™ connection to the GuardLogix safety controller. The GuardLogix controller drops out the redundant
contactors, and the hazard coasts to a stop. The safety contactors (K1 and K2) are connected to a pair of safety outputs
on a safety output module (1734-OB8S). The I/O module is connected via CIP Safety over an EtherNet/IP™ network to
the safety controller. After the hazard stops (you must determine how to monitor for the hazard stopping in your
application), the GuardLogix commands the MAB to unlock the door, which allows entry to the hazard. Once the
operator has completed the routine and repetitive maintenance, the operator closes the door and extends the bolt via the
handle. If the door is closed and the bolt is extended, a Lock button on the MAB can be used to send a signal to the
GuardLogix controller to lock the door by de-energizing the lock solenoid. In this example, the lock is Power-to-release.
The GuardLogix safety code monitors the status of the door by using the pre-certified safety instruction, Dual Channel
Input Stop with Test and Lock (DCSTL). The MAB provides a status bit that indicates that the door is closed, the bolt is
extended, and the bolt is locked. These status interlocks are monitored by the GuardLogix DCSTL.
When all safety input interlocks (the DCSTL is one of these interlocks) are satisfied, no faults are detected, and a safety
restart button on the MAB is pressed, a second GuardLogix certified function block called Configurable Redundant
Output (CROUT) controls and monitors feedback for a pair of 100S redundant contactors. The CROUT energizes
and de-energizes the contactors and monitors electromechanical feedback to make sure that both contactors operate
properly.
If a demand is placed on any other safety interlock, in this example it is the MAB E-stop, the redundant contactors are
dropped out. The Unlock Request button can then be used to request access to the hazard. The DCSTL safety
instruction makes sure that the hazard is stopped before the door is unlocked.
6 Rockwell Automation Publication SAFETY-AT129B-EN-P - November 2018
SAFEBK-RM002
SAFETY-AT056